The present invention is directed to modular analytical systems and, more particularly, to a method and system for determining the topology of a modular analytical system.
Instrument systems which comprise a plurality of modules are frequently used for tailor-made analytical systems which are adapted to one particular field of application. Some of the areas of applications which require a tailor-made profile of requirements are for example in the field of medicine and diagnostics. Highly specialized analyzers are often used in these fields which have to meet very high specifications. As a result of the specific performance features of the analyzers, it is often not possible for one analyzer alone to cope with the large number of requirements for an analytical system. Furthermore, additional devices are often necessary apart from the analyzers which are used to process and output data.
If a modular analytical system is for example used to analyse various clinical pictures, different parameters have to be determined depending on the clinical picture resulting in different requirements for the analytical system due to the field of application. Moreover, the manufacture of specific instruments that are used in such analytical systems is complicated and expensive and, hence, one aims to utilize the instruments to the highest possible extent. As a result, an analyzer has to be designed to be used for several systems and the number and type of analytical instruments varies in a modular analytical system. Hence, it is desirable to be able in each case to easily optimize an analytical system for a field of application and assemble it from several analyzers. Thus, for example, analyzers that are not required for standard analyses can be added or removed from the analytical system as required. Hence, the flexible use of an analyzer in a system not only enables a tailor-made solution with regard to the respective field of application but also an improved utilization of instruments. This ensures that highly specialized analytical systems can be provided in a cost-optimized manner. In addition, a central control of the analytical system can avoid additional costs since, for example, elements of the user interface (screens, loudspeakers, printers, etc.) no longer have to be provided for each individual analyzer. For this a central control makes the contact between the elements and the respective module.
Several methods and systems are described in the prior art to simplify the handling of modular analytical systems for the user. They often provide methods utilizing a central control unit which allow a determination of the arrangement of the individual modules relative to the central control unit as already described. Thus, the user does not have to carry out the otherwise necessary action of visually ordering the modules and their connection with the central unit and entering this relative arrangement into the system. Especially in the case of analytical systems in which modules are frequently exchanged and are operated by different users, a visual ordering of the relative arrangement of the modules and the respective input into the control unit would be a complicated and time-consuming process. The requirements that a modern modular analytical system has to meet of being easy and flexible to handle, would be significantly impeded by a visual procedure.
A method for determining the relative arrangement of modules is described in U.S. Pat. No. 5,404,460. This document discloses a system in which several modules are connected in series such that in each case the output of a module is connected to the input of the next module. The output of the last module is connected to a serial input of a central controller. The system has a common clock and a common reset line for all modules. A system reset and subsequent central clock-pulsing enables a specific reading and writing of the serial busses at exact times. In this process the first module generates a data packet when the system resets and gives itself an address (0). This data packet is now passed in phase from the first to the last module and finally to the central controller during which each module increases the packet contents by a data packet (+1) and gives it the corresponding address. As a result, the central controller receives information on the number and sequence of the modules in the overall system. The data packet corresponding to a respective address can also be used to transmit other data to the central controller which for example include a type name of the module. Hence, a display of the sequence of modules can simplify the identification of the modules for example by means of the type name and thus simplify an allocation by the user. A major disadvantage of this method is that each address allocation can only take place by resetting the entire system. Furthermore, the system is required in each case to have a line for a system reset and a clock line. Another serious disadvantage is that the system relies on a very particular clock cycling of its serial bus. Thus, with regard to an OSI layer model which is elucidated in the following it makes provisions about a bit transfer layer of its protocol. This imposes serious constraints on the freedom of the user to use industry standard protocols since, in particular, industry standardized busses are incompatible with such a method. A widespread industrial serial bus is for example the CAN bus. These special serial busses contain small data packets and are thus particularly robust compared to conventional serial busses. In these busses information is transferred at the protocol level of the OSI layer model. However, no address can be freely selected at this level. Hence, the method cannot be used for modules that are equipped with CAN busses as a standard.
Another method for determining topologies is described in International Patent Application No. WO 02/04675. This method is similar to the already described method since a data packet with address information is passed from module to module via a serial bus. The required synchronization is achieved by a separate control line. This gives rise to the already described disadvantages of the prior art since the method is incompatible with industry standards in order to achieve a specification of the protocol. Furthermore, an additional line is necessary in this case.